T cells are tightly controlled cellular machines that monitor changes in epitope presentation. Although T-cell function is regulated by means of numerous interactions with other cell types and soluble factors, the T-cell receptor (TCR) is the only structure on the T-cell surface that defines its antigen-recognition potential. Consequently, the transfer of T-cell receptors into recipient cells can be used as a strategy for the passive transfer of T-cell immunity. In this review, I discuss the pros and cons of TCR gene transfer as a strategy to induce defined virus- and tumour-specific T-cell immunity.